All posts tagged Droughts

Around the world, the litany of climate change related extreme weather events reached an extraordinary tempo over the past week. And it is becoming difficult for even climate change deniers to ignore what is increasingly obvious. The weather on planet Earth is getting worse. And human-caused global warming is, in vast majority, to blame…

More locally to the U.S., in the North Atlantic warmer than normal surface waters have fueled the odd development of hurricane Lee into a category 3 storm. It’s not really that strange for a major hurricane to develop in the Atlantic during September. It’s just that we’d tend to expect a storm of this kind to hit such high intensity in the Gulf of Mexico, or over the Gulf Stream, or in the Caribbean. Not at 30.6 N, 56.8 W in the Central North Atlantic south and east of Bermuda and strengthening from a weaker storm that was torn apart in the Inter-Tropical-Convergence-Zone, before drifting considerably to the north over what would typically be a less favorable environment.

Storms lasting for so long and hitting such high intensity produce a lot of energy. And the primary measure we have for that expended energy is ACE or Accumulated Cyclone Energy. 2017 is bound to achieve one of the highest ACE measures for any Atlantic Hurricane Season. Since 1851, only 8 years have seen an ACE value hit above 200. Present 2017 ACE is at 194 and climbing. Highest ever ACE values were recorded in 2005, at 250, and 1933 at 259.

If 2017 continues to produce strong, long-lasting storms over a record hot Atlantic, it is easily within striking distance of a record ACE year. The restrengthening of Lee to major hurricane status so far north and out in the Atlantic was yet one more surprise that shows how much energy the Atlantic is bleeding off this year. Such a tendency will likely continue through October but with storms probably not forming quite so frequently as during September and originating in regions closer to the Caribbean and U.S.

(Smoke covers large portions of the U.S. West following record heat in many locales. Image source: NASA Worldview.)

During the weekend, the heat shifted north and east — thrusting 90+ degree (F) temperatures into British Columbia where severe wildfires have been raging throughout the summer. As a result, fire intensity spiked once again and great plumes of smoke today blanketed hundreds of miles of western sky.

In total, more than 575,000 hectares have burned in British Columbia so far this year. This is about 6 six times the average rate of wildfire burning for a typically wet and cool region. An intensification of the fire regime that came on as temperatures warmed, climates changed, and indigenous plants found themselves thrust into conditions outside those they’re adapted to.

The extreme heat was brought on by the kind of combined Pacific Ocean warming and upper level high pressure ridge amplification that some researchers have linked to human-caused climate change. And the overall impacts of the system have been as outlandish as they are notable.

The drought’s center mass is near the Missouri River Basin — a primary water shed for the northern plains states. Since April, these key regions have seen as little as one quarter the usual precipitation amount. This equals the driest growing season ever recorded for some locations. And overall conditions are about as bad as they have been at any time in the past 100 years.

The result has been the emergence of a very intense flash drought. One of a type that has become more common as atmospheric temperatures have increased and as evaporation from waters and soils has intensified. At Lodgepole Montana, the heat and drought were enough to ignite a 422 square mile wildfire. Covering an area 1/3 the size of Rhode Island, the fire is Montana’s largest blaze since 1910. The fire is now, thankfully, 98 percent contained. More worrisome, the massive blaze is now accompanied by 9 smaller sister fires throughout the state. And all before the peak of fire season.

(Flash drought — a new phenomenon brought on by human-forced climate change — emerges in Montana. Image source: The US Drought Monitor and Grist.)

But regardless of Trump’s views on climate change or his related lack of preparedness, the damages and risks just continue mounting. Montana resident Sarah Swanson recently noted in Grist:

“The damage and the destruction is just unimaginable. It’s unlike anything we’ve seen in decades.”

Sadly, with atmospheric carbon levels in the range of 407 ppm CO2 and 492 ppm CO2e, and with fossil fuel burning still continuing, these kinds of devastating droughts, heatwaves, and fires will just keep on getting worse.

(More extreme variation in upper level wind speeds is an upshot of polar warming during boreal summer. The result is that risks of severe heatwaves, droughts, wildfires and floods increases as the Earth warms. Image source: Michael Mann, Penn State.)

From the study:

… our analysis of both historical model simulations and observational surface temperature data, strongly suggests that anthropogenic warming is impacting the zonal mean temperature profile in a manner conducive to wave resonance and a consequent increase in persistent weather extremes in the boreal summer.

What this means is that the new study provides still more evidence that the Jet Stream’s north to south variance is increasing during summer. As a result, it is enabling powerful heat domes to form in regions where winds run from south to north. In regions where the upper level winds run from north to south, it creates cooler zones in which powerful storms can flood large swaths of countryside. In other words, increasingly juxtapposed zones of extreme temperature anomalies and higher atmospheric instability and moisture loading tend to form more and more often. And this results in weather patterns that we have never really seen before.

(An Inconvenient Sequel is a call for action on climate change like we’ve never seen before. And the imperative to act on climate is now stronger than it ever was.)

The fact that the Mann study uses observational and model assessments to find that such changes are likely to very likely now being caused by human-forced warming and related polar amplification is a highly significant scientific finding. It adds one more attribution tie to the extreme weather events that we’ve been seeing with increasing frequency. A tie directly to global warming. And it does so through model studies that identify the underlying physical mechanisms at work. It’s a pivotal moment in the atmospheric sciences. And everyone needs to sit up and pay attention.

Credits:

Hat tip to Colorado Bob

Hat tip to Cate

Scientific hat tip to Dr Michael Mann

(Please support publicly-funded, non-special interest based science that is now under assault by the climate change denying Trump Administration)